1. Technical Field
The present invention relates generally to managing blood glucose levels, and in particular, to a computer implemented method for predicting and responding to a low blood glucose condition.
2. Description of Related Art
Diabetes is a chronic condition in which a person has high blood glucose (sugar), either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced. Insulin is a hormone that reduces blood glucose. Insulin is produced by the pancreas in response to increased blood glucose levels. Insulin causes cells in the liver, muscle and fat tissue to take up glucose from the blood, storing it as glycogen inside these tissues.
There are several types and causes of diabetes. Type 1 diabetes results from the body's failure to produce insulin. Type 2 diabetes results from insulin resistance, a condition in which cells fail to use insulin properly to reduce blood glucose properly, sometimes combined with an insulin deficiency. Gestational diabetes may occur in pregnant women, which may precede Type 2 diabetes. There are congenital diabetes due to genetic defects of insulin secretion, cystic fibrosis-related diabetes, steroid diabetes induced by high doses of glucocorticoids, and several other forms of diabetes.
Type 1 diabetes presently requires the person to inject insulin either with a syringe or an insulin pump to manage blood glucose levels. The other types of diabetes may also require the use of injected insulin depending on the severity of the condition and the ability of the person to manage their diabetes such as through diet and exercise. A normal range of blood glucose (sugar) is between 70 and 100 milligrams per deciliter (mg/dl) in the morning up to 135 to 140 mg/dl after a meal. When a person experiences elevated blood sugars over a period of time, various medical conditions can occur including damage to the heart, kidneys, nerves, eyes, and elsewhere throughout the body. As a result, a person with poorly managed diabetes may suffer from heart disease, kidney disease, blindness, circulation issues leading to amputations, etc.
Before the advent of the modern insulin pump, a diabetic would inject insulin using syringes, typically before and/or after a meal. The person would estimate the amount a calories being consumed and then calculate the appropriate amount of insulin to be injected. However, a person with diabetes could easily underestimate or overestimate the number of calories being consumed, and/or not take into account other influential factors, such as exercise or time since the last meal, thereby resulting in excessive swings in blood glucose levels.
Today many diabetics, particularly Type 1 diabetics, may use an insulin pump to deliver insulin. This pump can provide a steady infusion of insulin known as a basal rate between meals. The insulin pump can also provide an increased dose of insulin known as a bolus during meal periods based on the estimated amount of carbohydrates ingested, as entered by the diabetic into the insulin pump. The insulin pump recommends and implements an insulin dose based on the intended amount of food intake using a “Bolus Wizard” (a software program term known to many users of insulin pumps). The bolus wizard uses information provided by the patient's health care professional. For example, a ratio of 12:1 may apply for a given patient meaning the consumption of 24 grams of carbohydrates requires an injection of 2 grams of insulin.
Hypoglycemia or low blood glucose is an abnormally low amount of glucose in the blood. For a normal person, hypoglycemia may occur when their blood glucose drops below 70 mg/dl. For diabetics, hypoglycemia may occur at higher blood glucose levels such as 80 or even 90 mg/dl. Hypoglycemia may cause several initial symptoms such as double vision, increased heart rate, nervousness and confusion, shaking or trembling, sweating, etc. However, a diabetic may not show these initial symptoms of hypoglycemia, a condition referred to as hypoglycemia unawareness. Hypoglycemia may be caused by 1) too much insulin being released in the bloodstream such as by injection, 2) the body's glucose is used up too quickly such as by exercise, or 3) glucose is released into the bloodstream too slowly such as by inadequate consumption of carbohydrates. Hypoglycemia can be a dangerous condition, yet can be easily treated initially by consuming some carbohydrates such as by drinking a sweet soft drink. If not treated, hypoglycemia could result in confusion, fainting, seizures, coma and even death.